Challenges interface

With exams being a thing of the past, I have been able to resume work on our game. We have decided to change the UI a bit (farewell symmetry) in order to fit more spells when they become available and a turn order display (not visible just yet). Speaking of spells, they now each have a mana cost. The player is able to use multiple spells during their turn.

In addition to the blue mana meter, I have also added a collapsible challenge overview. We currently have about 10 challenges in the pipeline and intend to give the player 1-2 during each battle.